7. A porphyritic texture indicates that an igneous rock had

a. an intrusive origin.

b. an extrusive origin.

c. two different cooling rates.

d. formed at a mid-ocean ridge.

extrusive rocks.

Explanation:

When an igneous rock contains large crystals of minerals surrounded by the fine grained or glassy material (set in a matrix of glassy part). The texture is known as Porphyritic texture and the large crystals are known as Phenocrystals and the fine grained or glassy part is called as Ground mass.

When this Porphyritic texture showing igneous rocks are known as Porphyrites. The texture is largely found in volcanic and hypabassal rocks so these rocks are the extrusive rocks.