I need a formula to concatenate A1,B#,C1; and place the result in D2, D3, D...

A B C D
1 dog100 0000 red ""
2 0001 dog1000001red
3 0002 dog1000002red

A1: Does not change its location. It is an absolute reference.
It is in general format, a combination of text and a number. It is imported
that way.

B2: is a custom format number of the form "0000". I have to keep all the
digits. It is derived from a formula to increment the # in the previous
column, by one.

C3: Does not change its location. It is an absolute reference.
It is Text.

What I want is to end up with D2, D3,.. a combination of text and value,
derived by combining A1,B...,C1.
Then copy the formula down the D column, so it will referentialy calculate
the next answer.

Can someone help me put together text + numbers that increment?

Thanks,
Bob