[R] QuantMod and XML

[Robert Sherry]

I am trying to use the package quantmod to get option quotes in R. 
Therefore, I executed the following two commands:
         library ("quantmod" )
         getOptionChain("AAPL")
The first one worked but the second one produced the following error 
message:
         Error in getOptionChain.yahoo(Symbols = "AAPL") :
         package:“XML”cannot be loaded.
Therefore, I am thinking I need to install the package XML. To do so, I 
executed the following command:
         install.packages( "XML" )
However, that command failed because it could not find the package XML. 
The following URL:
         https://cran.r-project.org/web/packages/XML/XML.pdf
indicates to me that it does exist.

I am hoping somebody can tell me what I am doing wrong.

Thanks
Bob