如何编写可在Moodle中正常展示的RMarkdown数值+图表单选习题？

• 在RStudio中使用knitr编写RMarkdown习题，包含两类题目：
  • 数值题：要求输入相关系数，正确答案为代码中的corr1
  • 单选题：要求选择对应数据的图表，正确答案为grafico1.png
• 现有代码导入Moodle后，图表选项无可选单选按钮，无法正常交互

library(ggplot2)
library(exams) # 确保加载exams包以生成Moodle兼容题型

# 生成数据与图表的核心代码（保留原逻辑）
Concentration = c(7.1,82.9)
r.sq  = 0
while (r.sq <0.85) {
x = runif(33, min(Concentration),max(Concentration))
b = runif(1,-3,3)+rnorm(33,0,0.25)
a = ifelse(max(b)<0, -min(b)*max(x),0)
data = data.frame(Concentration = round(x,2), Reaction_time = round(a+b*x,2))
z = lm(data$Reaction_time~data$Concentration)
summa = summary(z)
r.sq = summa$r.squared
}
corr = round(cor(data$Concentration,data$Reaction_time),2)

corr1 = corr
r.sq  = 0
while (r.sq <0.85 | abs(corr1)<abs(corr)) {
x = runif(33, min(Concentration),max(Concentration))
b = runif(1,-3,3)+rnorm(33,0,0.25)
a = ifelse(max(b)<0, -min(b)*max(x),0)
data1 = data.frame(Concentration = round(x,2), Reaction_time = round(a+b*x,2))
z = lm(data1$Reaction_time~data1$Concentration)
corr1 =  round(cor(data1$Concentration,data1$Reaction_time),2)
summa = summary(z)
r.sq = summa$r.squared
}

corr2 = corr
r.sq  = 0
while (r.sq <0.85 | abs(corr2)<abs(corr)) {
x = runif(33, min(Concentration),max(Concentration))
b = runif(1,-3,3)+rnorm(33,0,0.25)
a = ifelse(max(b)<0, -min(b)*max(x),0)
data2 = data.frame(Concentration = round(x,2), Reaction_time = round(a+b*x,2))
z = lm(data2$Reaction_time~data2$Concentration)
corr2 =  round(cor(data2$Concentration,data2$Reaction_time),2)
summa = summary(z)
r.sq = summa$r.squared
}

corr3 = corr
r.sq  = 0
while (r.sq <0.85 | abs(corr3)<abs(corr)) {
x = runif(33, min(Concentration),max(Concentration))
b = runif(1,-3,3)+rnorm(33,0,0.25)
a = ifelse(max(b)<0, -min(b)*max(x),0)
data3 = data.frame(Concentration = round(x,2), Reaction_time = round(a+b*x,2))
z = lm(data3$Reaction_time~data3$Concentration)
corr3 =  round(cor(data3$Concentration,data3$Reaction_time),2)
summa = summary(z)
r.sq = summa$r.squared
}

write.csv(data,'concentration_vs_rxtime_q2.csv', row.names = FALSE)

p1 = ggplot(data, aes(x=Concentration, y=Reaction_time)) + geom_point()
p2 = ggplot(data1, aes(x=Concentration, y=Reaction_time)) + geom_point()
p3 = ggplot(data2, aes(x=Concentration, y=Reaction_time)) + geom_point()
p4 = ggplot(data3, aes(x=Concentration, y=Reaction_time)) + geom_point()

png('grafico1.png', width=380, height=248, units='px', pointsize=12)
p1
dev.off()

png('grafico2.png', width=380, height=248, units='px', pointsize=12)
p2
dev.off()

png('grafico3.png', width=380, height=248, units='px', pointsize=12)
p3
dev.off()

png('grafico4.png', width=380, height=248, units='px', pointsize=12)
p4
dev.off()

Determine the correlation coefficient:
##ANSWER1##

Choose the right plot for the data:
- ![](grafico1.png)
- ![](grafico2.png)
- ![](grafico3.png)
- ![](grafico4.png)

Meta-information
================
extype: cloze
exclozetype: num|schoice
exsolution: `r corr1`|1000
exname: mod10_q1

• 将单选题的编号列表（1.、2.）改为破折号开头的无序列表：exams包生成Moodle兼容题型时，schoice类型的选项必须用无序列表（-或*开头）才能被识别为可选择项，进而生成单选按钮
• 确保exclozetype设置为num|schoice，对应数值题和单选题的组合题型
• exsolution中1000表示四个选项里第一个为正确答案，与grafico1.png对应

内容的提问来源于stack exchange，提问作者Eugenio Guerrero Ruiz