Which ANOVA design should i choose? my choices are ANCOVA, Nested Design,Random Effects, Fixed Effects, and Mixed Effects.

Que. A textile company weaves a fabric on a large number of looms. It would like the looms to be homogeneous so it obtains a fabric of uniform strength. The process engineer suspects that there may be significant variations in strengths between looms. To investigate this, the engineer selects four looms at random and makes four strength determinations on the fabric manufactured on each loom.