The correct answer is I received set of gifts of personalized stationery.
Stationery is termed as a mass noun which refers to manufactured writing materials which are commercial. For example, writing implements, envelopes and cut paper.
We can say that stationery are material which can be written by hand or even by use of an equipment. For example printers and computers.
Stationery can be used in embossing, printing, and in engraving.
I am assuming that horses' is plural.
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If it were singular, it would be horse's.
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Sinces is it written s',it is plural.
The answer would be, It can be boring and can reduce emotional effect.