What does this map imply about the reasons for the massive Allied invasion of Europe in June of 1944?

Question

anonymous · Answer

A.  A successful invasion was difficult because the Axis powers controlled almost all of mainland Europe.
 B. The operation was forced to gain access to Western Europe through the northern coast of Spain.
 C. The German line of defense along the coasts of Western Europe was weakest along the border of Norway.
 D. The Allied forces were forced to use paratroopers because they could not use ground troops in the invasion.

anonymous · Answer

@FEARLESS_JOCEY @Jamierox4ev3r @chrissyC. @starlord6200

anonymous · Answer

Can anyone help please? I'm confused, I think it's C. but not 100%

anonymous · Answer

yea its c

anonymous · Answer

@amistre64 @AlexAwesome @blxckxx @BK_201 @heavenfun13 @horsegirl325 @Hannahfitz

anonymous · Answer

@starlord6200 thanks so much!

anonymous · Answer

dont mention it

anonymous · Answer

Sorry I couldn't help, it told me to log into something which I cannot