How do mirna recognize a particular target mrna?

the rna processing complexes edit the mirna base pair sequence by changing the identity of bases so it can base pair with the target mrna.
the mirna and mrna have the same sequence so they base pair.
the mirna sequence is complementary to the mrna sequence so they base pair.
the binding of mirna complex to risc alters the risc complex so these proteins bind directly to the mrna.

The miRNA sequence is complementary to the mRNA sequence so they base pair.

Explanation:

miRNA or microRNA is is a small non-coding RNA molecule  that is involved in RNA silencing and post-transcriptional regulation of gene expression. mi RNA performs its function by base-pairing with complementary sequences in mRNA.

As a result of complementary binding between miRNA and mRNA the gene can be silenced by:   mRNA cleavage or by destabilization of the mRNA by shortening of its poly(A) tail.

b. the carbon cycle ensures living things have a source of hydrogen