4. Magma can be created from mantle rock when:
a. Temperature rises c. Water is added
b. Pressure lowers d. All of the above

Thae answer is all of the above because magma can be created when hit, liquid rock intrudes into earth’s cold crust. As the liquid rock solidifies, it loses its heat to the surrounding crust. Much like hot fudge being poured over cold ice cream, this transfer of heat is able to melt the surrounding rock (the “ice cream”) into magma.

Well, a and b together would be negative. b alone would also be negative.